Wastewater Management in the City of Onkaparinga

Many suburbs in the Onkaparinga council area are not serviced by SA Water Sewer, subsequently wastewater generated by each premises must be managed by alternate means.

Townships such as McLaren Vale and Willunga are serviced by council owned and operated Community Wastewater Management Systems (CMWS).

Properties not serviced by these systems must discharge their wastewater on-site via approved land application methods such as soakage trenches and irrigation areas.

The installation or alteration of any wastewater system that is not covered by SA Water must be approved by Council and a wastewater works application needs to be submitted.

It is recommended that you research and select a wastewater system best suited to your location and circumstances prior to submitting an application, as the type of wastewater system selected will impact how you can use your land.

Installing an on-site wastewater system

Are you building a new home in an unsewered area? Do you need to upgrade your failing wastewater system? If so, this fact sheet is designed to provide you with information on what is involved and the different options you need to consider when choosing your wastewater system.

Changes to the Regulations and Codes for wastewater management in South Australia

On June 16th 2013 the new SA Public Health Act 2011, SA Public Health (Wastewater) Regulations 2013 and On-site Wastewater Systems Code commenced. Any wastewater applications received after this commencement date will be assessed under the new legislation.

Key changes in the new Regulations and Code include:

Councils are now the approving authority for alternative wastewater systems such as permanent greywater systems, reed beds and composting toilets.

Certificates of compliance (COC’s) are required to be submitted for all work undertaken in areas where the local council is the relevant authority. COC’s must be submitted to council within 28 days of completion of work.

Persons servicing wastewater systems (such as aerobic wastewater treatment systems) will be required to complete a training course specified by the DHA. The 3 day course is now being offered by TAFE SA at the Regency Park School of Plumbing. For further information telephone TAFE SA on (08) 8348 4206

Plumbers will be required to install irrigation systems connected to wastewater treatment systems and provide a COC for this work. It is expected that the engineers report will contain information on the irrigation system components.

A Wastewater Engineers’ assessment report will be necessary for all sites (including aerobic wastewater treatment systems installations). The full requirements for the report can be found in the On-site Wastewater Systems Code and will include the type of system, site and soil details, the size of disposal / recycled water area required (Note that the 200 m2 irrigation requirement has been removed with the area to be determined by the engineer), recreation area requirements

Community Wastewater Management Systems (CWMS)

Is a system for the collection and management of wastewater generated in a town, regional area or other community.

Onkaparinga council owns and operates its own CWMS in the towns of Willunga, McLaren Vale, McLaren Flat, Clarendon, Maslin Beach and parts of Sellicks Beach. Properties connected to the council CWMS require a septic tank before the wastewater is discharged to the community sewer system.

There are two privately owned CWMS located in the Bluewater Estate Sellicks Beach and the Aldinga Eco Village. Septic tanks are not required in these subdivisions but a wastewater works application is still necessary for all plumbing work and connection into the CWMS.

To find out whether you are in a CWMS area, contact the Environmental Health section on 8384 0666.

Wastewater Treatment Systems

In most cases, wastewater must undergo some form of appropriate treatment prior to discharge to a land application system or CWMS. Common types of treatment systems are described below

Septic tank

is an underground watertight tank generally constructed of concrete or plastic which is usually divided into at least two compartments. The tank receives all sewage and separates the solid portion of the waste water from the liquid portion. The liquid portion (effluent) passes out of the tank after approximately 24 hours. The tank performs three functions:

It acts as a settlement chamber for solid materials

It allows some bacterial breakdown of waste materials to occur

It acts as a storage chamber for undigested solid materials which must be removed periodically (usually every 4 years)

There are several methods of disposing of the effluent after it has passed through the septic tank. A common onsite disposal method is subsurface soakage (absorption trenches). If a CWMS connection is available the effluent will overflow into the common drainage system and taken away for treatment.

Aerated Wastewater System (AWTS)

An aerobic wastewater treatment unit is designed to treat septic tank effluent to a level suitable for surface irrigation within the site.

The unit may incorporate a septic tank or it may be separate.

Following primary treatment in the septic tank, the effluent is treated by a process or aeration, settling and disinfection and then pumped to a dedicated irrigation area as required.

Aerobic Sand Filter

Sand filters achieve a similar result to aerobic wastewater treatment systems but the treatment process is different.

The effluent from the septic tank is filtered through a sand layer which provides natural aeration and biological oxidation through aerobic and nitrifying organisms.

From the disinfection chamber the reclaimed water is pumped to the dedicated irrigation area.

Reed Bed

Secondary treatment system consisting of shallow ponds or channels which have been planted with aquatic plants, they rely upon natural microbial, biochemical, physical and chemical processes to treat wastewater. Treated effluent is disposed of via subsurface soakage.

Composting Toilet

A device that receives and treats human excreta, domestic organic matter and bulking agents, using natural aerobic stabilisation and disinfection processes to produce a product that is not a public health risk. Composted material must be buried for at least 6 months after a completed composting period of 12 months in the composting toilet system.

Greywater systems

Greywater is wastewater generated from bathrooms (showers, baths, spas, and hand basins), laundries (washing machines, troughs) and kitchens (sinks and dishwashers). However, kitchen water can contain food particles, grease, oils and fats and its use is not recommended (particularly without treatment).

The quality of greywater can be highly variable due to factors such as number of household occupants, their age, lifestyle, health, water source and products used (such as soaps, shampoos, detergents)

Permanent greywater systems

such as diversion devices or treatment systems, or any device attached to plumbing, can increase the use of greywater. However due to potential risks associated with grey water, permanent devices require installation approval from the Council.

Manual bucketing and temporary diversion

Manual bucketing onto lawn and garden areas using water from the bathroom or laundry, or temporary use of a hose manually fitted to the washing machine outlet hose, is permitted subject to the following advice:

Don’t use greywater from washing clothes soiled by faeces or vomit, for example, nappies.

Don’t store untreated greywater for more than 24 hours, as bacteria and organic contaminants in greywater will cause it to turn septic and produce strong and offensive odours.

Don’t use greywater if others in the household have diarrhoea or an infectious disease, as this could increase the risk of other people becoming ill.

Don’t use greywater to irrigate fruit, vegetables, or areas where fruit can fall to the ground and be eaten.

Avoid splashing of greywater and wash your hands before eating or drinking or smoking.

Keep children away from areas watered with greywater until it has soaked into the ground.

Trade waste

Trade Waste is defined as the liquid waste from any industry, business, trade or manufacturing premises, other than domestic sewage

Non-residential premises that generate trade waste may require a pre-treatment device or apparatus to be installed to ensure that prohibited discharges do not occur to the CWMS or to the environment via an onsite wastewater system.

Prohibited discharges

Unless otherwise approved by the council, no person should permit or cause any of the following discharges into an on-site wastewater system:

Any storm water, including roof and rainwater tank overflow, and surface drainage waters

Any back flush waters from a swimming pool or water softener

Any discharge or back flush from a spa bath/pool in excess of 680L capacity or in the case of a CWMS, unless otherwise accepted by the relevant authority

Any sanitary napkin, clothing, plastic material or liner

Any trade waste

Any petrol or other flammable or explosive substance whether solid, liquid or gaseous

Any other matter or substance which, in the opinion of the relevant authority, would impair the effective working of an on-site wastewater system or CWMS

Wet wipes (including those marketed as ‘flushable’) and baby wipes

SA Water sewer areas

Where properties are located in a proclaimed sewerage area, wastewater from the premises must be directed to SA Water Sewer. To find out whether your property has access to the SA Water sewer network call 1300 650 950

Applying for approval to install or alter a wastewater system

Pursuant to the SA Public Health (Wastewater) Regulations 2013, all on-site wastewater systems and alterations to on-site wastewater systems are subject to a wastewater works approval. Refer to the South Australian Department for Health and Ageing ON-SITE WASTEWATER SYSTEMS CODE (the Code) for further information to assist in the completion of this application form. The Code can be accessed online at

Systems can also be designed using the Australian/New Zealand Standard 1547 (AS/NZS 1547) - On-site domestic wastewater management*.

*Using a combination of approach in chapter 8 of the Code and AS/NZS 5147 is not acceptable

Each application must include two copies of a detailed sanitary plumbing and drainage lay-out (refer to Section 8 of the Code), a site and soil report (refer to Section 3.6.1 of the Code) and the appropriate application fee.

Applications where necessary, must include a detailed assessment of the land capability of the site via a soil report (i.e. the suitability of the site for treatment and disposal/reuse of domestic wastewater).

Please note that failure to provide the correct information will result in delays in obtaining an approval it is recommended that you ensure all relevant information is submitted with your application, see checklist below for details on what must be submitted.